Unless otherwise indicated herein, the description in this section is not prior art to the claims in this application and is not admitted to be prior art by inclusion in this section.
In an image forming apparatus such as a printer, toner inside of a developing device is carried by a developing roller (a toner carrier) to be supplied to a photoreceptor drum (an image carrier) so as to perform development.
In this image forming apparatus, if a printing rate on an image to be formed is low, a small amount of toner is used for development. This reduces turnover of toner within the developing device. If this situation repeats, the toner within the developing device is excessively charged. This may cause reduction in image density or fogging, thus reducing the image quality.
In response to this situation, although the toner itself has been improved, reduction in image quality has not been reliably reduced at present.
On the other hand, a technique that forcibly discharges toner within a developing device for refresh has been proposed.